Question

My ant project generates an “output” folder which contains the outputs of multiple runs and I would like to diff them all against files located in an “expected” folder (these lasts have the exact the same name as the ones in the output folder). I tried that:

<apply executable="diff">
    <fileset dir="${output.dir}" />
    <arg value="-u" />
    <srcfile />
    <arg value="${expected.dir}/" />
    <srcfile />
    <redirector>
         <outputmapper type="merge" to="result.out" />
    </redirector>
</apply>

But I have two problems:

First I am not allowed to put two <srclist /> in one <apply>, so how can I use two times the name of the current file treated in one <apply>?

Second I am not able to get the output of my <apply> in one single file. I tried different ways (putting the output argument in the <apply> tag…) but it always seems to only store the last execution of the apply. How can I append the result of each diff in one single file?

And I don’t want to have to install anything else (so no ant-contrib with foreach).

Thanks.

Answer 1

This works for me:

<delete file="result.out" />
<apply executable="diff" force="yes" output="result.out" append="true">
    <fileset dir="${output.dir}" />
    <srcfile />
    <targetfile />
    <mapper type="glob" from="*" to="${expected.dir}/*" />
</apply>

Some explanation:

• The apply task targetfile element lets you specify a second arg that is derived from the srcfile via the mapper.
• To get the merged output use the output attribute and set append true. Note that you may need to delete the output file (i.e. truncate it) otherwise on rerun you’ll not get a clean slate.
• I fiddled with the arg list for diff to suit my OS, instead of passing expected.dir and the target file as successive elements, the mapper merges them into a single full path to the ‘right hand’ file for the diff.